I have an arduino with a simple 3-pin IR receiver like you would find at radio shack. The receiver works fine when the power supply to the arduino is 6 AA batteries, but not when the power supply is a wall plug with 7.5V DC. It seems to work for a few seconds, then not at all. I'm using the IRRemote library here: http://www.arcfn.com/2009/08/multi-protocol-infrared-remote-library.html
To further help describe the problem, the Arduino is controlling a bunch of LEDs, and when I use PWM to turn down the brightness of these LEDs, the IR receiver ceases to work as well, either when battery powered or wall powered. When the PWM is not being used and the LEDs are full on, it's not a problem.
I'm not sure how to debug or fix this. I'm sure that the IRRemote is using a different timer than the PWM, and the power source exhibiting the problem when the PWM is off confirms that that's not the root cause. I suspect that there may be some kind of noise introduced by the wall power supply or the rapid switching of the LEDs. Both the receiver and all of the LEDs are tied to the same ground pin of the Arduino. What can I do to separate or filter the receiver so that it is not affected by the power supply or PWM?